More than 12,000 people have already signed our petition calling on the Government to keep controls on Bulgarian and Romanian workers coming here.

Our telephone switchboard and website were also inundated with expressions of support.

And in a further indication of the strength of public opposition to large-scale immigration, 98 per cent of readers taking part in a snap Daily Express phone poll agreed that Britain “should close its borders to ALL new migrants”.

Strict controls on EU migrants are due to lapse at midnight on December 31.

Prime Minister David Cameron says that we are obliged like other European Union member states to lift these restrictions.

They were imposed when Bulgaria and Romania joined the EU in 2007 and were designed to put a strict limit on their citizens’ rights to work here.

David Cameron says the UK is obliged to lift the restrictions [PA]

But campaigners estimate that as many as 70,000 a year could move here from the two countries once the controls are lifted.

Our petition urges Mr Cameron to defy the EU and insist that Britain will keep the restrictions in place.

Yesterday, the Prime Minister’s official spokesman indicated that although Mr Cameron firmly believed it was right to put the controls in place in 2007, he did not see any scope for extending them beyond the New Year deadline.

The spokesman said: “They are transitional controls and they do come to an end.”

Stressing the Government had acted to reduce the pressures of immigration, he added: “The Prime Minster would say that more widely we need to bring net migration down. And we have a policy as a Government of doing that.”

Nick Clegg was challenged over the Express' campaign on his weekly radio show [GETTY]

One caller to Mr Clegg’s show asked: “What is the Government actually going to do about immigration?

“Could we have a straight answer as to why the loophole hasn’t been closed down, why the numbers have not been reduced, what is actually going on? What are Brussels not allowing you to do?”

The europhile Lib Dem leader said he was aware of people’s concerns but suggested they were misplaced.

He claimed the scale of Romanian and Bulgarian arrivals would be nowhere near the massive numbers of eastern Europeans who came when their countries joined the EU in 2004, and the Labour government put no limits in place.

Nick Ferrari, host of the “Call Clegg” phone-on show, then directly challenged the Deputy PM on air about our Crusade. Mr Clegg insisted the Government had cut net immigration by about a third and made some “very, very significant changes” to the system.

People are backing our campaign to halt the flood of eastern European migrants [TIM CLARKE]

He added: “What I want to see is an immigration system that means that we are open to people that come to this country, that want to help out and want to work, and want to pay their taxes, want to play by the rules.

“Our public services depend on people coming to this country. The NHS would collapse overnight if we simply pulled up the drawbridge, and we should continue to give British citizens the freedom to go, as they do actually in very large numbers, to live elsewhere.

“So you can’t suddenly just put up a barrier but it’s got to be done in a way which is administratively competent and that people have confidence in.”

Mr Ferrari pressed Mr Clegg on whether he agreed with estimates that up to 70,000 Romanians and Bulgarians a year would flood into Britain.

The Deputy PM said he did not know and that the Government had no intention of repeating Labour’s mistake of issuing inaccurate forecasts.

He conceded: “I don’t want to deny people’s concern. It’s palpable. A lot of people have raised it with me.

“And I totally understand, having been given these, as it turned out to be misleading estimates which underestimated the number of people who came here from central and eastern Europe (in 2004).

“We shouldn’t automatically assume that it’s going to be exactly the same scale (as 2004), not least because there are a number of Bulgarian and Romanian communities, large communities, in other parts of the EU. That often suggests that is where people would tend to go. But of course we’re going to keep a very close eye on this.”

Later Mr Ferrari, who had hosted another show before the Call Clegg programme, told the Daily Express 95 per cent of people contacting him yesterday had backed our Crusade.

He said: “The moment we talked about it, the calls started flooding in. People are concerned about the sheer level of migration.”

Tory MP Peter Bone’s Private Member’s Bill calling for the restrictions on Bulgarian and Romanian immigration to remain in force, is due for its Second Reading on November 29.